Tadpoles as dengue mosquito (Aedes aegypti) egg predators

Abstract

Mosquito eggs survive drought conditions while harboring pathogens, perpetuating diseases through seasons. Biological control of mosquitoes using vertebrates mostly highlights the role of larvivorous fish. Here we show that tadpoles with different life-history characteristics predate on Aedes aegypti (vector mosquito of dengue virus) eggs. We did four experiments involving tadpoles of Polypedates cruciger to determine: (i) egg laying preference of female mosquitoes, in normal water, water in which tadpoles were previously present, and water in which tadpoles were present at the time of experiment; (ii) survivability of mosquito eggs in tanks in presence vs. absence of tadpoles; (iii) egg predation through direct observation (video-recording) and gut content analysis; (iv) if egg predation is prevalent among different species of tadpoles of four species of randomly selected genera, Bufo, Ramanella, Euphlyctis and Hoplobatrachus were subjected to experiment (iii) only. We show that mosquitoes have a preference to lay eggs in tadpole water and that tadpoles destroy such eggs laid. Direct observations substantiate that all tadpole species tested are mosquito egg predators. With about seven thousand frog species worldwide, living in a diversity of aquatic habitats where fish cannot reach, the role of tadpoles in biological control of mosquitoes can be significant than currently understood.